Fastening method and apparatus

ABSTRACT

A fastening method comprising using a control apparatus to select a first upsetting volume of an upsetting die, using a punch to push a first fastener into a workpiece and using the upsetting die to upset the first fastener, then using the control apparatus to select a second upsetting volume of the upsetting die, using the punch to push a second fastener into a workpiece and using the upsetting die to upset the second fastener, or using the punch and the upsetting die to form a clinch joint.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The term “fastener” is used herein to include rivets, screws, slugs,weld studs, mechanical studs and other types of fastening devices.

II. Description of Related Art

Known fastening apparatus include a nose assembly into which a rivet ispassed from a rivet storage location, and from which the rivet isinserted into a workpiece by a punch. The fastening apparatus includesan upsetting die which is located beneath the workpiece and which isconfigured to upset the rivet when the rivet is inserted into theworkpiece. The volume and shape of the upsetting die is chosen toprovide a desired degree of upsetting such that the rivet adopts adesired shape when it is inserted into the workpiece. The feeding of atleast two different rivets (i.e. rivets having different dimensions) tothe nose assembly is already known. When it is desired to fasten adifferent workpiece or a different location on a workpiece (e.g. adifferent combination of material types and/or thicknesses) or insert adifferent rivet (i.e. a rivet with different dimensions or hardness)into the workpiece, it is frequently necessary to remove the upsettingdie and replace it with a different upsetting die which has a shape andvolume that is more suited to the different rivet and/or differentcombination of material types and/or thicknesses.

It is desirable to provide a fastening method which overcomes ormitigates a problem associated with known fastening methods.

SUMMARY OF THE INVENTION

According to first aspect of the invention there is provided a fasteningmethod comprising using a control apparatus to select a first upsettingvolume of an upsetting die, using a punch to push a first fastener intoa workpiece and using the upsetting die to upset the first fastener,then using the control apparatus to select a second upsetting volume ofthe upsetting die, using the punch to push a second fastener into aworkpiece and using the upsetting die to upset the second fastener, orusing the punch and the upsetting die to form a clinch joint.

The method allows two or more different rivets (i.e. rivets havingdifferent dimensions and/or hardnesses) to be inserted into a workpiece(or different workpieces) without having to use two or more separatefastening apparatus. This is advantageous because it providesflexibility which allows a production line to be designed with a lowerquantity of fastening apparatus than would otherwise be required. Sincea lower quantity of fastening apparatus may be used, a correspondinglylower quantity of peripheral apparatus associated with implementation ofthe fastening apparatus may be used (for example robots and materialshandling equipment). The method thus allows a cheaper production line tobe designed.

The method also allows two or more different rivets (i.e. rivets havingdifferent dimensions and/or hardnesses) to be inserted into a workpiece(or different workpieces) using the same fastening apparatus withoutremoving the upsetting die and replacing it with an alternativeupsetting die. This provides a significant efficiency improvement, sinceoperation of a fastening apparatus does not need to be interrupted inorder to allow the upsetting die to be changed. Instead, operation ofthe fastening apparatus may continue almost immediately, a small timebetween the insertion of fasteners being required in order to allow thevolume of the upsetting die to be changed. This small time may forexample be less than the time required for the fastening apparatus orworkpiece to be moved from a first fastener insertion location to asecond fastener insertion location, in which case changing the volume ofthe upsetting die does not reduce the rate of operation of the fasteningapparatus.

The method also allows rivets having the same dimensions to be insertedinto workpieces having different material combinations (e.g. materialtypes and/or thicknesses) without having to remove the upsetting die andreplace it with an alternative upsetting die. Instead, the volume of theupsetting die is changed in order to accommodate the different materialcombinations of the workpiece.

The method allows switching between fastener insertion (e.g. insertionof self-piercing rivets) and clinching, thereby avoiding the need toprovide a fastening apparatus for fastener insertion and a separatefastening apparatus for clinching.

The selection of the upsetting volume of the upsetting die by thecontrol apparatus may be automated.

The selection of the upsetting volume of the upsetting die may be basedon previously stored information and/or feedback.

The method may further comprise again selecting the first upsettingvolume of the upsetting die, and using the punch to push a subsequentfastener into a workpiece and using the upsetting die to upset thesubsequent fastener.

The upsetting volume of the upsetting die may be fixed during upsettingof the fasteners.

Selecting the upsetting volume of the upsetting die may compriseselecting the depth of the upsetting die.

The upsetting die may be at least partially formed by a surface of a rodlocated in a bore, the rod being moved within the bore to change theupsetting volume of the upsetting die.

The position of the rod within the bore may be determined by anadjustable end stop.

The adjustable end stop may comprise a cam which is moveable between aplurality of configurations which determine the position of the rodwithin the bore.

The cam may be a plate which is configured to rotate about an axis ofrotation.

The upsetting die may be at least partially formed by a surface of a rodlocated in a bore in a housing, the housing being moved relative to therod to change the upsetting depth of the upsetting die.

The upsetting die may be at least partially formed by a surface of a rodlocated in a bore in a housing and at least partially formed by a sleevelocated between the rod and the housing, the sleeve being moved relativeto the rod and the housing to change the upsetting diameter of theupsetting die.

The first fastener and the second fastener may have different dimensionsand/or hardnesses.

The first fastener and the second fastener have may have the samedimensions, and the workpiece into which the second fastener is pushedmay comprise a combination of materials which is different to thecombination of materials which comprises the workpiece into which thefirst fastener is pushed.

The selection of the second upsetting volume of the upsetting die may beperformed whilst the punch and upsetting die are moving between a firstfastening location and a second fastening location, or whilst theworkpiece is being moved between a first fastening location and a secondfastening location.

The upsetting volume of the upsetting die may be selected using anactuator.

The feedback may include one or more of movement of the punch, forceexperienced by the punch and force experienced by the upsetting die.

The control apparatus may determine and selects an upsetting volume ofthe upsetting die which will provide improved fastening based upon thefeedback.

The method may further comprise selecting a volume which is differentfrom the first upsetting volume or the second upsetting volume andthereby separating or assisting in separation of workpiece material andthe upsetting die.

According to a second aspect of the invention these is provided afastening method comprising using a punch to push a fastener into aworkpiece and using an upsetting die to upset the first fastener, orusing the punch and the upsetting die to form a clinch joint, the methodfurther comprising changing the volume of the upsetting die oncefastening has been completed and thereby separating or assisting inseparation of workpiece material and the upsetting die.

Changing the volume of the upsetting die may comprise reducing thevolume of the upsetting die.

According to a third aspect of the invention these is provided a methodof manufacturing a product or a sub-assembly comprising fastening one ormore workpieces in accordance with the first or second aspects of theinvention.

According to a fourth aspect of the invention there is provided afastening apparatus comprising a punch and an upsetting die, wherein theupsetting volume of the upsetting die is adjustable and wherein thefastening apparatus further comprises an actuator and control apparatuswhich are configured to adjust the upsetting volume of the upsettingdie, the control apparatus being capable of selecting an upsettingvolume of the upsetting die individually for each fastener which isinserted into a workpiece.

The control apparatus may be configured to select the upsetting volumeof the upsetting die in an automated manner.

The control apparatus may be configured to select the upsetting volumeof the upsetting die based on previously stored information and/orfeedback.

The actuator and control apparatus may be configured to fix theupsetting volume of the upsetting die during upsetting of the fasteners.

The control apparatus may be capable of selecting an upsetting volumewhich is suitable for forming a clinch joint.

The upsetting die may be at least partially formed by a surface of a rodlocated in a bore, the rod being movable within the bore to change theupsetting volume of the upsetting die.

The apparatus may further comprise an adjustable end stop which isconfigured to determine the position of the rod within the bore duringupsetting of a fastener.

The adjustable end stop may comprise a cam which is moveable between aplurality of configurations which determine the position of the rodwithin the bore.

The cam may be a plate which is configured to rotate about an axis ofrotation.

The upsetting die may be at least partially formed by a surface of a rodlocated in a bore in a housing, the housing being moveable relative tothe rod to change the upsetting depth of the upsetting die.

The upsetting die may be at least partially formed by a surface of a rodlocated in a bore in a housing and is at least partially formed by asleeve located between the rod and the housing, the sleeve beingmoveable relative to the rod and the housing to change the upsettingdiameter of the upsetting die.

The apparatus may further comprise one or more sensors which areconfigured to provide feedback to the control apparatus which ismeasured during fastening,

The control apparatus may be configured to determine and select anupsetting volume of the upsetting die which will provide improvedfastening based upon the feedback.

The one or more sensors may be configured to measure one or more of themovement of the punch, force experienced by the punch and forceexperienced by the upsetting die.

The control apparatus may be configured to change the upsetting volumeof the upsetting die whilst the fastening apparatus is moving between afirst fastening location and a second fastening location, or whilst theworkpiece is moving between a first fastening location and a secondfastening location.

The control apparatus may be configured to select a volume which isdifferent from the upsetting volume after a fastener has been upset,thereby separating or assisting in separating workpiece material and theupsetting die.

According to a fifth aspect of the invention there is provided afastening system comprising the fastening apparatus of the fourth aspectof the invention, and further comprising a rivet feeding system and acontrol system.

According to a sixth aspect of the invention there is provided afastening apparatus comprising a punch and an upsetting die, wherein thevolume of the upsetting die is adjustable and wherein the fasteningapparatus further comprises an actuator and control apparatus which areconfigured to adjust the volume of the upsetting die, the controlapparatus being configured to select an upsetting volume of theupsetting die to upset a fastener inserted into a workpiece or to form aclinch joint, the control apparatus being further configured to changethe volume of the upsetting die once fastening has been completed andthereby separate or assist in separating workpiece material and theupsetting die.

The change of the volume of the upsetting die may be a reduction of thevolume of the upsetting die.

According to a seventh aspect of the invention there is provided afastening apparatus comprising a punch and an upsetting die, wherein theupsetting volume of the upsetting die is adjustable and wherein thefastening apparatus further comprises an actuator and control apparatuswhich are configured to adjust the upsetting volume of the upsettingdie, the control apparatus being configured to select a first upsettingvolume of the upsetting die to upset one or more fasteners inserted intoa workpiece, and to then select a second upsetting volume of theupsetting die to upset one or more fasteners inserted into a workpieceor to form a clinch joint.

According to an eighth aspect of the invention there is provided afastening method comprising selecting a first upsetting volume of anupsetting die, using a punch and the upsetting die to form a firstclinch joint in a workpiece, then selecting a second upsetting volume ofthe upsetting die and using the punch and the upsetting die to form asecond clinch joint in the workpiece.

The second upsetting volume of the upsetting die may be determined andselected based upon feedback received during formation of the firstclinch joint. This may be done for example in order to provide animproved clinch joint.

According to a ninth aspect of the invention there is provided afastening apparatus comprising a punch and an upsetting die, wherein theupsetting volume of the upsetting die is adjustable and wherein thefastening apparatus further comprises an actuator and control apparatuswhich are configured to adjust the upsetting volume of the upsettingdie, the control apparatus being configured to select a first upsettingvolume of the upsetting die to form a first clinch joint in a workpiece,and to then select a second upsetting volume of the upsetting die toform a second clinch joint.

The control apparatus may be configured to determine and select thesecond upsetting volume of the upsetting die based upon feedbackreceived during formation of the first clinch joint. This may be donefor example in order to provide an improved clinch joint.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the present invention will now be described withreference to the accompanying drawings by way of example only, in which:

FIG. 1 is a perspective view of a fastening apparatus according to anembodiment of the present invention;

FIG. 2 is two cross-sectional views of an upsetting die assemblyaccording to an embodiment of the present invention in a firstconfiguration;

FIG. 3 is a cross-sectional view of the upsetting die assembly of FIG. 2in a second configuration;

FIG. 4 is a cross-sectional view of the upsetting die assembly of FIG. 2in a third configuration;

FIG. 5 is a cross-sectional view of an upsetting die assembly accordingto an alternative embodiment of the invention in a first configuration;

FIG. 6 is a cross-sectional view of the upsetting die assembly of FIG. 5in a second configuration;

FIG. 7 is a cross-sectional view of part of an upsetting die assemblyaccording to a third embodiment of the invention;

FIG. 8 is a cross-sectional view of an upsetting die assembly accordingto a fourth embodiment of the invention in a first configuration;

FIG. 9 is cross-sectional view of the upsetting die assembly of FIG. 8in a second configuration;

FIG. 10 is a cross-sectional view of an upsetting die assembly accordingto a fifth embodiment of the invention in a first configuration;

FIG. 11 is an exploded view of part of the upsetting die assembly ofFIG. 10;

FIG. 12 is a cross-sectional view of the upsetting die of FIG. 10 in asecond configuration;

FIG. 13 is a cross-sectional view and a perspective view of an upsettingdie assembly according to an alternative embodiment of the invention ina first configuration;

FIG. 14 is a cross-sectional view of the upsetting die assembly of FIG.13 in a second configuration;

FIG. 15 is a cross-sectional view of an upsetting die assembly accordingto an alternative embodiment of the invention in a first configuration;

FIG. 16 is a cross-sectional view of the upsetting die assembly of FIG.15 in a second configuration;

FIG. 17 is a cross-sectional view of an upsetting die assembly accordingto an alternative embodiment of the invention;

FIG. 18 is a cross-sectional view of an upsetting die assembly accordingto an alternative embodiment of the invention; and

FIG. 19 is a cross-sectional view and a perspective view of an upsettingdie assembly according to an alternative embodiment of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1 of the drawings, a fastening apparatus according toan embodiment of the invention comprises a rivet setting tool 61 that issupported by an upper jaw 62 of a C-frame 63 above an upsetting dieassembly 64 disposed on a lower jaw 65 of the frame. Rivets are insertedby the tool into a workpiece (not shown) supported over the upsettingdie assembly 64 as is well known in the art.

The setting tool 61 comprises an electric drive 66 (other types of drivesuch as hydraulic or pneumatic can be used) that operates to drive areciprocal punch (hidden in FIG. 1) in a cylindrical housing 67 and anose assembly 68. The reciprocal punch is used to insert rivets from thenose assembly 68 into a workpiece. Rivets are supplied under air or gaspressure from a bulk feeder (not shown) via a delivery tube 69. Suppliedrivets pass through the delivery tube 69 to a feeder assembly 76 that ismounted immediately adjacent to the nose assembly 68. The rivets arethen transferred from the feeder assembly 76 into the nose assembly 68from where they are inserted into the workpiece. When rivets areinserted into the workpiece they are upset by the upsetting die assembly64.

A fastening system may comprise the fastening apparatus described above,and may further comprise a rivet feeding system 70 and a control system71. The rivet feeding system is configured to deliver rivets via aconnector 72 of the fastener apparatus to the delivery tube 69. Thecontrol system 71 is configured to control delivery of rivets to thenose assembly 68, and is configured to control operation of thereciprocal punch.

FIG. 2 shows an upsetting die assembly 164 according to an embodiment ofthe invention. FIG. 2a shows the upsetting die assembly in cross-sectionviewed from one side, and FIG. 2b shows the upsetting die assembly incross-section but rotated through 90 degrees. The upsetting die assembly64 comprises a housing 100 within which a generally cylindrical bore 102is provided. A rod 104 is located within the bore 102. The rod 104 isprovided at an upper end with a substantially flat upper surface 106from which a pip 108 projects. An upper end of the rod 104 has adiameter which substantially corresponds with the diameter of the bore102 such that the upper end of the rod 104 does not move laterallywithin the bore (although a small degree of lateral movement may arisefrom tolerances in the size of the rod and the bore during theirmanufacture). A lower end 122 of the rod 104 is bevelled to assistinsertion of the rod into the bore 102. The rod 104 includes a portionhaving a reduced diameter 110 which connects an upper portion 111 of therod with a central portion 112, the central portion having a diameterwhich is substantially equal to the diameter of the upper portion. Alower portion 114 of the rod has a reduced diameter and connects to thecentral portion 112 at a step 116 at which the diameter of the rodincreases. A helical spring 118 abuts against the step 116. An oppositeend of the helical spring 118 abuts against a step 120 at which thediameter of the bore 102 reduces. The helical spring 118 resilientlybiases the rod 104 upwards. The reduced diameter of the bore 102substantially corresponds with the diameter of the lower portion 114 ofthe rod 104.

A lowermost end 122 of the rod 104 abuts against a rotatably mountedadjustable end stop 124 when a fastener is being inserted into aworkpiece. However, when a fastener is not being inserted into aworkpiece (i.e. when no workpiece is present in the upsetting die), thehelical spring 118 pushes the rod 104 upwards so that it is no longer incontact with the adjustable end stop 124. The adjustable end stop 124 isprovided with four substantially flat surfaces, each of which isarranged to provide a contact surface which receives the lowermost end122 of the rod 104. The adjustable end stop 124 is located in an opening126 in the housing 100 and is provided with an opening 128 whichreceives an actuator rod (not shown) that is used to rotate theadjustable end stop. The adjustable end stop opening 128 is generallycircular but includes a slot which may help to ensure that the actuatorgrips the adjustable end stop 124 and is able to rotate it (rather thanrotating within the adjustable end stop opening).

A threaded bore 132 is provided on one side of the housing 100, and athreaded plug 134 is held in the threaded bore. The threaded plug 134extends into the bore 102 at a location which corresponds with thelocation of the reduced diameter section 110 of the rod 104. Thethreaded plug 134 thus restricts movement of the rod 104, for examplepreventing the rod from falling out of the bore 102.

In use, the adjustable end stop 124 has a first configuration as shownin FIG. 2a . The helical spring 118 is in compression and pushes the rod104 upwards such that its lowermost end 122 is raised above a surface125 of the adjustable end stop 124. However, when a fastener is beinginserted into a workpiece the rod 104 is pushed downwards against thebias of the helical spring 118 so that the bottom surface 122 of the rodpresses against the surface 125 of the adjustable end stop 124 (pressurebeing exerted by a punch of the fastening apparatus). The resilientbiasing force provided by the helical spring 118 is less than the forceneeded to upset a rivet. Thus, the helical spring 118 has beencompressed such that the rod is pressed against the surface 125 of theadjustable end stop 124 before upsetting of the rivet takes place.Consequently, the adjustable end stop 124 determines the position of therod 104 during upsetting of a fastener. This is the position shown inFIG. 2.

When the adjustable end stop 124 is in the first configuration, as shownin FIG. 2, the flat upper surface 106 of the rod is located apredetermined distance below an upper end of the bore 102. Thepredetermined distance may for example be 1 mm or some other suitabledistance. The flat upper surface 106 of the rod 104 and the pip 108 ofthe rod, together with a collar 130 formed by an upper end of the bore102, form an upsetting die which upsets rivets during operation of thefastening apparatus. The diameter of the collar 130, which provides aninner side wall of the upsetting die, may be suitable for themanufacture of a desired range of riveted and/or clinched joints. Theupsetting die has a volume which is fixed during upsetting of the rivet,the volume being determined by the distance between the flat uppersurface 106 of the rod 104 and the top of the bore 102. This distance isdetermined by the height of the surface 125 of the adjustable end stop124 upon which the rod 104 rests, which in turn is determined by thevertical diameter of the adjustable end stop.

The volume of the upsetting die defined by the flat upper surface 106,pip 108 and collar 130 may be suited for upsetting a rivet havingparticular dimensions. It may be desired to change the volume of theupsetting die in order to allow a rivet having different dimensions tobe used by the fastening apparatus.

FIG. 3 shows the rod 104 and adjustable end stop 124 in an intermediateconfiguration which is between the first operational configuration shownin FIG. 2 and a second operational configuration shown in FIG. 4. InFIG. 3 the adjustable end stop 124 has been rotated through 45°. Thehelical spring 118 pushes the rod 104 upwards, thereby providing a gapbetween the lowermost end 122 of the rod and the adjustable end stop124. This allows the adjustable end stop 124 to be rotated freelywithout it having to push the rod 104 upwards. This reduces wear of theadjustable end stop 124 and wear of the lowermost end 122 of the rod104.

In FIG. 4 the rotatably mounted adjustable end stop has been rotatedthrough 90° and is in a second operational configuration. The adjustableend stop 124 provides a surface 129 onto which the rod 104 is pressedwhen a fastener is being inserted into a workpiece. The verticaldiameter of the adjustable end stop 124 is greater than the verticaldiameter of the adjustable end stop in the configuration shown in FIG. 2(the smaller diameter of the adjustable end stop is now the horizontaldiameter of the adjustable end stop). As a result, during upsetting of arivet the rod 104 lies further up the bore 102, and the distance betweenthe flat upper surface 106 of the rod and an upper end of the bore 102is reduced. The flat upper surface 106 and pip 108 of the rod 104together with the collar 130 of the housing 100 thus form an upsettingdie which has a smaller volume than the upsetting die of FIG. 2. Thisallows rivets having different dimensions to be inserted into aworkpiece (for example rivets having a shorter shank).

As may be appreciated from comparison of FIG. 2a and FIG. 4, theadjustable end stop opening 128 moves upwards when the adjustable endstop 124 is rotated from the first configuration to the secondconfiguration. The upward movement of the adjustable end stop opening128 is half of the upward movement of the rod 104, and may for examplebe 0.5 mm. The actuator (not shown) which is used to rotate theadjustable end stop 124 is configured to be able to accommodate thismovement of the adjustable end stop opening 128.

A substantially flat surface 131 of the adjustable end stop 124 which isopposite to the rod 104 is in contact with a bottom surface of theopening 126 of the housing 100. The adjustable end stop 124 is formedfrom a material which is sufficiently strong to resist significantdeformation when pressure is applied to the rod 104 during upsetting ofa rivet. Pressure which is applied via the rod 104 to the adjustable endstop 124 passes from the adjustable end stop to the lowermost surface ofthe opening 126 and from there is transferred to a lower jaw 65 of theC-frame 63 (see FIG. 1).

The embodiment of the invention allows the volume of the upsetting dieto be changed rapidly by rotation of the adjustable end stop 124 through90°. This allows the fastening apparatus to switch rapidly frominsertion of a first fastener type to insertion of a second fastenertype (e.g. rivets having different dimensions). It also allows thefastening apparatus to switch rapidly from insertion of a fastener intoa workpiece comprising a first material combination to insertion of afastener (e.g. having the same dimensions) into a workpiece comprising asecond material combination. The term “material combination” may referto the thicknesses of materials which comprise the workpiece and/or mayrefer to the types of material which comprise the workpiece. Rotation ofthe adjustable end stop 124 by the actuator (not shown) may becontrolled by a control apparatus (not shown).

As mentioned above, the helical spring 118 is in compression andseparates the rod 104 from the adjustable end stop 124 when no downwardforce is being applied to the helical spring. This reduces wear of theadjustable end stop 124 and the helical spring 118. A further advantageof the helical spring 188 is that it may bias the rod 104 to push debrisout of the upsetting die after insertion of a fastener. If the threadedplug 134 is unscrewed to allow free movement of the rod 104, then thehelical spring 118 will push the rod upwards so that it is proud of thehousing 100 thereby allowing the rod to be easily removed from thehousing (e.g. to replace the rod). The helical spring 118 may also alloweasier assembly of the upsetting die assembly.

Although a helical spring 118 is used to separate the rod 104 from theadjustable end stop 124, any suitable biasing means may be used toseparate the rod from the adjustable end stop. Although the biasingmeans provides the advantage that it allows the adjustable end stop 124to rotate freely, it is not essential that a biasing means is provided.For example, the rod 104 may rest upon the adjustable end stop 124, theadjustable end stop displacing the rod during rotation of the adjustableend stop.

The adjustable end stop 124 is provided with four substantially flatsurfaces onto which the rod 104 may press during operation of thefastening apparatus. In an alternative arrangement the adjustable endstop 124 may be provided with a different number of substantially flatsurfaces, for example six substantially flat surfaces, eightsubstantially flat surfaces or more. The substantially flat surfaces maylie on opposite sides of an axis of rotation of the adjustable end stop124 such that when a first substantially flat surface is positioned toprovide a contact surface for the rod 104 an opposite substantially flatsurface is positioned to provide a contact surface for the housing 100.

The surfaces of the adjustable end stop 124 onto which the rod 104presses in use are substantially flat. This is advantageous because itallows a substantially flat lowermost end 122 of the rod 104 to providea substantial contact area between the rod and the adjustable end stop124, thereby allowing force applied to the rod during fastener upsettingto be transmitted into the adjustable end stop. It also allows theadjustable end stop 124 to provide a substantial contact area betweenthe adjustable end stop and the bottom surface of the opening 126 of thehousing 100, thereby allowing force applied to the adjustable end stopto be transmitted into the housing. The surfaces of the adjustable endstop 124 may have some other suitable shape (i.e. not substantiallyflat), with the shape of the lowermost end 122 of the rod 104 and thebottom surface of the opening 126 of the housing 100 being appropriatelyshaped to provide a substantial contact area with the rod.

The actuator (not shown) may be configured to always rotate theadjustable end stop 124 in the same direction (e.g. clockwise as shownin FIGS. 2-4). Alternatively, the actuator may be configured to rotatethe adjustable end stop 124 in both the clockwise and anticlockwisedirections.

As described above, the adjustable end stop opening 128 moves verticallyduring rotation of the adjustable end stop 124. The vertical movementmay be half of the change in height of the adjustable end stop 124caused by the rotation, or may be some other amount (this will dependupon the shape of the adjustable end stop). In some arrangements theadjustable end stop opening 128 may remain stationary in the verticaldirection during rotation of the adjustable end stop 124.

The adjustable end stop 124 provides surfaces with different heightsupon which the rod 104 rests during upsetting of a fastener. Althoughthe adjustable end stop shown in FIGS. 2-4 has a particular shape, theadjustable end stop may have any suitable shape. The shape may providedifferent distances between a rod receiving surface of the adjustableend stop and a lowermost surface of the adjustable end stop. An exampleof an alternative adjustable end stop which has these properties isshown in FIGS. 5 and 6.

FIG. 5 shows in cross-section an upsetting die assembly 264 according toan alternative embodiment of the invention. The upsetting die assembly264 is similar to the upsetting die assembly shown in FIGS. 2-4, andcomprises a housing 200 provided with a generally cylindrical bore 202within which a rod 204 is provided. The rod 204 includes a substantiallyflat upper surface 206 and a pip 208 which projects from thesubstantially flat upper surface. The rod 204 includes a portion havinga reduced diameter 210 which connects an upper portion 211 of the rodwith a central portion 212, the central portion having a diameter whichis substantially equal to the diameter of the upper portion. A lowerportion 214 of the rod has a reduced diameter and connects to thecentral portion 212 at a step 216 at which the diameter of the rodincreases. A helical spring 218 abuts against the step 216. An oppositeend of the helical spring 218 abuts against a step 220 at which thediameter of the bore 202 reduces. The helical spring 218 resilientlybiases the rod 204 upwards. The reduced diameter of the bore 202substantially corresponds with the diameter of the lower portion 214 ofthe rod 204. The lowermost end 222 of the rod 204 is bevelled to assistinsertion of the rod into the bore 202. A threaded plug 234 extends intothe bore 202 and acts to limit upward movement of the rod 204.

The housing 200 is provided with an opening 226. Unlike the embodimentshown in FIGS. 2-4 a rotatable adjustable end stop is not provided inthe opening 226, but instead a stepped adjustable end stop 240 isprovided in the opening. The stepped adjustable end stop 240 comprises afirst substantially planar surface 242 and a second substantially planarsurface 244, the first surface being lower than the second surface. Thesurfaces 242, 244 are provided on a tongue which extends from a block246 that is connected to an actuator (not shown). The position of thestepped adjustable end stop 240 may be controlled by a control apparatus(not shown).

A step 243 between the first substantially flat surface 242 and thesecond substantially flat surface 244 is sloped or profiled. The slopeor profile of the step 243 may for example correspond with the cornerprofile of a lowermost end 222 of the rod 204 (as shown in FIG. 5).

The helical spring 218 resiliently biases the rod 204 upwards and awayfrom the stepped adjustable end stop 240. However, when a fastener isbeing inserted into a workpiece during operation of the fasteningapparatus, the rod 204 is pushed downwards and presses against thestepped adjustable end stop 240. The resilient bias provided by thehelical spring 218 is less than the force required to upset a rivet, andconsequently during upsetting of a rivet the position of the rod withinthe bore 202 is determined by the position of the stepped adjustable endstop 240. When the stepped adjustable end stop 240 is in a firstconfiguration, as shown in FIG. 5, the rod 204 has a first positionwhich is determined by the height of the first surface 242 of thestepped adjustable end stop. The substantially flat upper surface 206and pip 208 of the rod 204 together with a collar 230 formed by an upperend of the bore 202 establish an upsetting die having a particularvolume. This upsetting die volume may be appropriate for fastening usinga rivet having particular dimensions.

If it is desired to use the fastening apparatus to fasten using rivetshaving different dimensions (e.g. having a shorter shank), then the rod204 may be moved from the first configuration shown in FIG. 5 to asecond configuration shown in FIG. 6. This is achieved by moving thestepped adjustable end stop 240 such that the second surface 244 islocated beneath the rod 204. Since the second surface 244 is higher thanthe first surface 242, the rod 204 is further up the bore 202 when arivet is being upset. As a consequence of the upward displacement of therod 204, an upsetting die is formed by the substantially flat uppersurface 206, pip 208 and collar 230 which has a smaller volume than theupsetting die formed when the stepped adjustable end stop and rod are inthe first configuration.

Although the stepped adjustable end stop 240 shown in FIGS. 5 and 6 isprovided with two substantially flat surfaces 242, 244 onto which therod 204 presses during insertion of fasteners, the stepped adjustableend stop may be provided with three, four, five, six or moresubstantially flat surfaces.

Although the surfaces 242, 244 are described as being substantiallyflat, the surfaces may have some other form. The lowermost end 222 ofthe rod 204 may have a corresponding form (e.g. selected to provide asubstantial contact area between the rod and the stepped adjustable endstop).

The helical spring 218 is used to separate the rod 204 from the steppedadjustable end stop 240 and provides the advantage that it allows thestepped adjustable end stop 240 to move freely. Although a helicalspring 218 is shown, any suitable biasing means may be used to separatethe rod 204 from the stepped adjustable end stop 240. It is notessential that a biasing means is provided. For example, the rod 204 mayrest upon the stepped adjustable end stop 240, the adjustable end stopdisplacing the rod during movement of the adjustable end stop.

A third embodiment of the invention is shown in cross-section in FIG. 7.FIG. 7 shows part of a fastener upsetting die assembly 364 held on alower jaw 65 of a C-frame. A rod 304 is held within a housing 300 whichis connected to the lower jaw 65 of the C-frame by bolts 356. Asubstantially flat upper surface 306 of the rod and a collar 330 form anupsetting die. In this embodiment the rod 304 is not provided with a pipat an uppermost surface. However, a pip may be provided. The rodincludes a reduced diameter portion 310 which may receive a plug (notshown) which passes through a threaded bore 311 in the housing 300 (theplug being used to retain the rod and/or limit movement of the rod ifdesired). Although this embodiment does not include a spring whichbiases the rod 304 upwards, a spring may be provided.

A lowermost end 322 of the rod 304 rests upon a sloped surface 350 of anadjustable end stop which comprises a sloped cam 351. The lowermost end322 of the rod may be considered to be a cam follower. A biasing means(not shown) may be provided to bias the rod 304 against the sloped cam351. The sloped cam 351 is located in an opening 326 in the housing 300and is translatable in a direction which is substantially perpendicularto the direction of movement of the rod 304. The cam 351 is moved usingan actuating rod 352 which is controlled by an actuator 354 (e.g. apneumatic cylinder, piezo-electric actuator, stepper-motor or the like).Movement of the cam 351 by the actuator 354 may be controlled by acontrol apparatus (not shown). The opening 326 which receives the slopedcam 351 is sufficiently large to allow the sloped cam to be insertedinto the opening with a range of positions which provide a desired rangeof positions of the rod 304.

The lowermost end 322 of the rod 304 is provided with a slope whichsubstantially corresponds to the sloped surface 350 of the sloped cam351. This allows substantially all of the lowermost end 322 of the rod304 to be in contact with the sloped surface of the sloped cam 351. Thisis advantageous because it allows force applied to the rod 304 duringfastening to be transmitted to the sloped cam 351 over a relativelylarge surface area (compared with the surface area if only a smallportion of the lowermost end of the rod was in contact with the slopedcam).

In use, the height of an upper end of the rod 304, and thus the volumeof an upsetting die formed by the uppermost surface 306 of the rod andthe collar 330 of the housing, is controlled by the position of thesloped cam 351. When the sloped cam 351 is moved such that the slopedsurface 350 pushes the rod 304 upwards then this reduces the volume ofthe upsetting die. Conversely, when the sloped cam is moved such thatthe sloped surface 350 allows the rod 304 to move downwards thisincrease the volume of the upsetting die.

Unlike the embodiments shown in FIGS. 2-6, the sloped cam 351 allowsmore than two positions of the rod 304 to be selected. The sloped cam351 may allow variation in a continuous manner of the position of therod 304. This may in turn allow variation in a continuous manner of thevolume of the upsetting die formed using the rod 304.

In the embodiments shown in FIGS. 2-6 the lowermost end 122, 222 of therod 104, 204 rests upon a substantially flat surface when fastening isperformed by the fastener. Consequently, when force is applied by apunch onto the rod 104, 204 during fastening, this force is transmitteddownwards through the adjustable end stop 124, 240 and does not includea component which tends to induce movement of the adjustable end stop.In contrast to this, in the embodiment shown in FIG. 7 a component offorce exerted on the rod 304 during a fastening operation may act topush the sloping cam 351 towards the actuator 354. The surface 350 ofthe sloping cam 351 and/or the lowermost end 322 of the rod 304 may havea surface finish which generates friction between them (for example arough surface finish), thereby inhibiting horizontal movement of the camwhen downwards force is exerted on the rod. If the friction which isgenerated is sufficiently high, this may prevent horizontal movement ofthe cam 351 during insertion of a fastener. The angle of the slopingsurface 350 of the sloping cam 351 will determine what proportion offorce exerted on the rod 304 tends to push the sloping cam 351 towardsthe actuator 354. The slope may be selected to be sufficiently shallowthat the force exerted on the rod 304 during a fastening operation isnot sufficient to cause movement of the sloping cam 351 (taking in toaccount the friction which is provided by the surface finish of the camand/or the lowermost end 322 of the rod 304). Additionally oralternatively, the actuator 354 may be configured to withstand forceexerted upon it during a fastening operation.

FIG. 8 shows in cross-section an upsetting die assembly 464 according toa further alternative embodiment of the invention. Also shown in FIG. 8is part of a lower jaw 65 of a C-frame (see FIG. 1) to which theupsetting die is attached. The upsetting die assembly 464 comprises arod 404 located in a bore 402 formed in a housing 400. A substantiallyflat upper surface 406 of the rod together with a collar 430 formed byan upper end of the bore 402 forms an upsetting die. Although no pip isshown on the upper surface 406 of the rod 404, a pip or other shapedfeature may be provided. The bore 402 includes a step 405 at a lowerportion 403 which increases the diameter of the bore such that it mayaccommodate a helical spring 418. The rod 404 includes a lower portionwith an increased diameter 460. The helical spring 418 abuts against theincreased diameter portion 460 of the rod 404 and against the step 405in the bore 402. The helical spring 418 is under compression andresiliently biases the rod 404 downwards and into the bore 402.

A cam follower 462 is provided at a lowermost end of the rod 404. Thecam follower has a sloped surface 465 which is configured to cooperatewith a ball 466 which forms part of an actuation apparatus. The ball 466is provided with a flat surface 467 which is in contact with the slopedsurface 465 of the cam follower 462. The actuation apparatus comprises acam 470 which is connected to a rotary actuator 472, the ball 466 beingheld in a recess 471 provided in the cam. Rotation of the cam 470 by theactuator 472 may be controlled by a control apparatus (not shown). Thecam 470 may be considered to be an adjustable end stop.

The rotary actuator 472 may for example be pneumatic, and may thusinclude connectors 474 configured to allow pneumatic pressure to pass tothe rotary actuator and control its orientation. Alternatively, therotary actuator 472 may be electric (for example the rotary actuator maybe a stepper-motor).

The cam follower 462 and rod 404 are free to move in the axial direction(i.e. up and down), but are not free to rotate. Rotation of the camfollower 462 is prevented by a ball 484 which projects from a horizontalbore 485 in the housing 401 and which is received in a verticallyoriented slot 486 in the cam follower 462. The ball 484 is held in placeby a plug 487 provided in the horizontal bore 485. Thus, rotation of thecam 470 does not cause the cam follower 462 to rotate but instead forcesthe cam follower 462 to move up and down. The ball 466 is free to rotatein the recess 471 of the cam 470, thereby allowing the flat surface 467of the ball to remain in contact with the sloped surface 465 of the camfollower 462. Allowing the flat surface 467 of the ball 466 to remain incontact with the sloped surface 465 of the cam follower 462 in this wayis advantageous because the flat surface provides a surface area throughwhich force may be transmitted during insertion of a fastener into aworkpiece.

The housing 400 includes a flared lowermost portion 401, part of whichis received in the lower jaw 65 of the C-frame. Bolts 475 are used tosecure the housing 400 to the lower jaw 65.

In use, the cam 470 is rotated using the rotary actuator 472, whereuponthe ball 466 either pushes the rod 404 upwards or allows the rod 404 tomove downwards under bias of the helical spring 418 via the interactionof the flat surface 467 of the ball 466 with the sloped surface 465 ofthe cam follower 462. When the rotary actuator is in the configurationshown in FIG. 8, the flat surface 467 of the ball 466 is in contact witha thinnest portion of the sloped surface 465 of the cam follower 462.The rod 404 thus is withdrawn to a maximum extent into the bore 402,thereby forming an upsetting die having a maximum volume (as determinedby the position of the substantially planar upper surface 406 of therod). FIG. 9 shows the upsetting die assembly 64 when the cam 470 hasbeen rotated through 180°. As may be seen from FIG. 9, the flat surfaceof the ball 467 is now in contact with the thickest portion of thesloped surface 465 of the cam follower 462. The ball 466 has thus pushedthe cam follower 462 and the rod 404 upwards to a maximum extent,thereby forming an upsetting die which has a minimum volume. The rotaryactuator 472 may move the cam 470 to orientations which are intermediatethe orientations shown in FIGS. 7 and 8, thereby forming upsetting dieshaving other volumes. The rotary actuator 472 and cam 470 may allowvariation in a continuous manner of the position of the rod 404. Thismay in turn allow variation in a continuous manner of the volume of theupsetting die formed using the rod 404.

The helical spring 418 ensures that the cam follower 462 remains incontact with the ball 466 when the cam 470 is rotating, thereby ensuringthat the orientation of the ball changes such that the flat surface 467of the ball remains pressed against the cam follower.

The actuator 472 may be capable of rotating the cam 470 through 360°. Amovement of 2.5 mm of the rod 404 within the bore 402 may for example beobtained through rotation of the cam 470 through 180°.

An upsetting die assembly 564 according to a further alternativeembodiment of the invention is shown in FIGS. 10-12. The upsetting diecorresponds generally with the upsetting die assembly 64 shown in FIGS.8 and 9, and corresponding reference numerals are used for correspondingcomponents. In this embodiment a cam 580 and a cam follower 582 areprovided. The cam 580 may be considered to be an example of anadjustable end stop. However, no ball is provided between the cam 580and the cam follower 582. Instead, the cam 580 and cam follower 582 areprovided with surfaces 581, 583 which have corresponding shapes, theshapes comprising partial helixes. FIGS. 10 and 12 show the upsettingdie assembly in cross-section in a first configuration and a secondconfiguration. FIG. 11 shows the cam 580 and cam follower 582 in anexploded perspective view (the cam and cam follower being in the firstconfiguration). The orientation of the cam 580 may be controlled by acontrol apparatus (not shown).

As may be seen from FIG. 11, the surface 581 of the cam 580 comprisestwo partial helixes, each of which extends for just under 180°. Thepartial helixes are separated by a slot 584 which extends between them.The slot 584 may allow easier manufacturing of the cam surface 581 thanwould be the case if the slot were not present. The surface 583 of thecam follower 582 has a shape which corresponds with the shape of thesurface 581 of the cam 580.

In common with the embodiments shown in FIGS. 8 and 9, the cam follower582 is free to move in the axial direction but is not free to rotate.Rotation of the cam follower 582 is prevented by a ball 584 whichprojects from a horizontal bore 585 in the housing 401. A plug 587 holdsthe ball 584 in the horizontal bore 585. The ball 584 is received in avertically oriented slot 586 in the cam follower 582 and prevents thecam follower from rotating.

When the cam 580 has the orientation shown in FIG. 10, the surfaces581,583 of the cam and the cam follower 582 are fully in contact withone another, and the cam follower 582 is at a lowermost position suchthat the rod 404 is withdrawn into the bore 402 to a maximum extent. Anupsetting die having a maximum volume is thus formed by a substantiallyplanar upper surface 406 of the rod and a collar 430 formed by anuppermost end of the bore 402. Rotation of the cam 580 is controlled byan actuator 472 which in turn is controlled by a control apparatus (notshown). When the cam 580 is rotated through for example 90°, as is shownin FIG. 12, a relatively thick portion of the cam follower 582 is incontact with a relatively thick portion of the cam 580. As a result, thecam follower 582 and the rod 404 are pushed upwards. An upsetting diehaving a reduced volume is thus formed by a substantially planar uppersurface 406 of the rod and a collar 430 formed by an upper most end ofthe bore 402. The construction of the surfaces 581, 583 using pairs ofpartial helixes provides the advantage that force being exerted on therod 404 during a fastening operation is transmitted through the camsurfaces on either side of a central axis which passes through the rod.

Rotation of the cam 580 by 90° may for example reduce the depth of theupsetting die by 3 mm. The depth may for example be reduced from 3 mm to0 mm. Where this is the case, upsetting die depth increments of 0.25 maybe obtained by rotating the cam 580 by 7.5°.

The cam 580 may be moved to orientations which are intermediate theorientations shown in FIGS. 10 and 12, thereby forming upsetting dieshaving other volumes. The cam 580 may thus allow variation in acontinuous manner of the position of the rod 404. This may in turn allowvariation in a continuous manner of the volume of the upsetting dieformed using the rod 404.

The embodiment shown in FIGS. 10-12 includes a helical spring 418 whichis under compression and keeps the surfaces 581, 583 pressed againsteach other. The helical spring is not necessary and the helical springmay be omitted, although this may allow the cam follower to move in anuncontrolled manner within the housing 401 (for example during movementof the fastening apparatus between fastening locations).

The surfaces of the cam and cam follower may have a shape which differsfrom the shape shown in FIGS. 10-12. The surfaces may be rotationallysymmetric for a rotation of around 180° about an axis which passesthrough the rod (e.g. two surfaces being provided on the cam). This willprovide the advantage that force being exerted on the rod 404 during afastening operation is transmitted through cam surfaces on either sideof the axis. The surfaces may be rotationally symmetric for a rotationof around 120° (or some other rotation) about an axis which passesthrough the rod (e.g. three or more surfaces being provided on the cam).This will provide the advantage that force being exerted on the rod 404during a fastening operation is transmitted through cam surfaces whichare distributed around the axis.

In a further alternative embodiment of the invention (not illustrated)the adjustable end stop may comprise a threaded shaft that is held in athreaded housing. The adjustable end stop may be moved axially withinthe housing by driving the adjustable end stop to rotate using a rotaryactuator. The axial movement of the adjustable end stop may cause axialmovement of the rod which forms part of the upsetting die, therebychanging the volume of the upsetting die. This may allow variation in acontinuous manner of the position of the rod. This may in turn allowvariation in a continuous manner of the volume of the upsetting dieformed using the rod.

In a further alternative embodiment of the invention (not illustrated)the rod which forms part of the upsetting die may be threaded and thebore in which the rod is held may be correspondingly threaded. In thisembodiment the rod may be moved axially within the bore by driving therod to rotate using a rotary actuator. This may allow variation in acontinuous manner of the position of the rod. This may in turn allowvariation in a continuous manner of the volume of the upsetting dieformed using the rod.

In a further alternative embodiment, instead of moving the rod withinthe bore to change the volume of the upsetting die, the rod may be heldstationary and the housing which defines the bore may be moved over therod to change the volume of the upsetting die. An example of this isshown in FIGS. 13 and 14. Referring to FIG. 13a , an upsetting dieassembly 664 comprises a rod 604 provided within a bore 602 in a housing600. The rod 604 extends beyond a lowermost end of the housing 600 andis held in a support structure 690. The support structure 690 may beheld in a lower jaw of a C-frame (not shown). The rod 604 is received ina bore 691 formed in the support structure 690. A threaded bore 632 isprovided on one side of the support structure 690, and a threaded plug634 is held in the threaded bore. The threaded plug 634 extends into areduced diameter section 692 of the rod 604. The threaded plug 634 thusholds the rod in the support structure 690 and prevents it from fallingout of the support structure. The diameter of the rod 604 reduces at astep 616. A helical spring 618 abuts against the step 616. An oppositeend of the helical spring 618 abuts against a step 620 at which thediameter of the bore 602 reduces.

The support structure 690 is provided with an opening 693, and a cam 640is provided in the opening. The cam 640 may be considered to be anexample of an adjustable end stop. The cam 640 is forked and is providedwith arms 694 which extend either side of the rod 604. Although only oneof the forks 694 is shown in FIG. 13a , both of the forks 694 may beseen in FIG. 13b . Each of the forks 694 comprises a first substantiallyplanar surface 695 and a second substantially planar surface 696. Thefirst surface 695 is lower than the second surface 696. The arms 694extend from a block 646 which is connected to an actuator (not shown).The position of the cam 640 may be controlled by a control apparatus(not shown).

The housing 600 is vertically moveable relative to the rod 604 and thesupport structure 690. A lowermost surface of the housing 600 is incontact with the cam 640. The helical spring 618 resiliently biases thehousing 600 downwards, thereby pushing the housing against the cam 640.

In use, as shown in FIG. 13a and FIG. 13b , the cam 640 may have aposition in which the second surface 696 of the arms 694 is locatedbeneath the housing 600.

The height of the housing 600 is thus determined by the height of thesecond surface 696 of the cam 640. An upsetting die is formed by asubstantially flat upper surface 606 of the rod 604, a pip 608 providedon the rod, and a collar 630 formed by an upper end of the housing 600.The upsetting volume of the upsetting die is determined by the height ofthe housing 600, which in turn is determined by the height of the secondsurface 696 of the cam 640.

If it is desired to use the fastening apparatus to fasten using a rivethaving different dimensions (e.g. having a shorter shank), then thehousing 600 may be moved from the first configuration as shown in FIGS.13a and 13b to a second configuration as shown in FIG. 14. This isachieved by moving the cam 640 such that the second surface 695 of thearms 694 is located beneath the housing 600. Since the second surface694 is lower than the first surface 696, the housing 600 is moveddownwards relative to the rod 604 thereby forming an upsetting die witha smaller upsetting volume.

A step 643 between the first surface 695 and the second surface 696 ofthe arms 694 is sloped. The slope of the step 643 may for examplecorrespond with a sloped edge provided at a lowermost end of the housing600. The sloped surface of the step 643 and the sloped surface of thehousing may allow the cam 640 to push the housing 600 upwards when thecam moves from the configuration shown in FIG. 14 to the configurationin FIGS. 13a and 13 b.

Although the arms 694 of the cam 640 each have two surfaces 695, 696upon which the housing 600 may rest, the arms may be provided with adifferent number of surfaces. For example, each arm may be provided withthree, four, five, six or more surfaces.

Although the surfaces 695, 696 are shown as being substantially flat,the surfaces may have some other form. The lowermost end of the housing600 may have a corresponding form (e.g. selected to provide asubstantial contact area between the housing and the surfaces).

Although a helical spring 618 is shown, any suitable biasing means maybe used. It is not essential that a biasing means is provided.

FIG. 15 shows in cross-section an upsetting die assembly 764 accordingto a further alternative embodiment of the invention. The upsetting dieassembly 764 is similar to the upsetting die assembly shown in FIGS.13-14, but provides a change of diameter of the upsetting die instead ofproviding a change of depth. A rod 704 is provided in a bore 702 in ahousing 700. The housing 700 is provided on a lower jaw of a C-frame(not shown). A movable sleeve 798 is provided between the 704 and thehousing 700. Unlike the embodiment shown in FIGS. 13 and 14, the housing700 is not moveable. An opening 793 is provided in the housing 700, theopening receiving arms 794 of a cam 740. The cam 740 may be consideredto be an example of an adjustable end stop. The arms 794 extend eitherside of the rod 704. Each arm comprises a first surface 795 and a secondsurface 796, the first surface 795 being lower than the second surface796. Each arm 794 is connected to a block 746 which is connected to anactuator (not shown). The position of the cam 740 may be controlled by acontrol apparatus (not shown). A step 743 is provided between the firstsurface 795 and the second surface 796 of each arm 794. The step 743 hasa slope which substantially corresponds with a slope 797 provided at alowermost surface of the sleeve 798.

The rod 704 is provided with a step 716 against which one end of ahelical spring 718 abuts. The sleeve 798 is provided with a step 720against which an opposite end of the helical spring 718 abuts. Thehelical spring biases the sleeve 798 downwards such that the sleevepushes against the arms 794 of the stepped cam 740.

702

The rod 704 is held in the bore 720 by a threaded bolt 734 which isreceived in a threaded bore 732 provided in a side of the housing 700.The threaded bolt 734 is received in a reduced diameter section 792 ofthe rod 704, and prevents the rod from falling out of the housing 700.The length of the threaded bolt 734 may be selected such that it extendsinto the reduced diameter section 792 of the rod 704 without pressingagainst the rod (e.g. to avoid bending the rod). Although the bore 702shown in FIG. 14 is significantly wider than the rod 704, the bore 702may be narrower and may for example have a diameter which issufficiently narrow that it prevents significant lateral movement of therod 702

A substantially flat upper surface 706 of the rod 704 together with apip 708 and a collar 731 formed by the sleeve 798 form an upsetting die.It may be desired to change the upsetting volume of the upsetting die,for example to use the fastening apparatus to fasten using rivets havingdifferent dimensions (e.g. having a longer or wider shank). This may beachieved by moving the sleeve 798 from the first configuration shown inFIG. 15 to a second configuration shown in FIG. 16. This is done bymoving the cam 740 such that the first surface 795 of the arms 794 islocated beneath the sleeve 798 instead of the second surface 796. Sincethe first surface 795 is lower than the second surface 796, the sleeve798 moves downwards under the resilient bias of the helical spring 718.As a result of the downward displacement of the sleeve 798, an upsettingdie is formed with an increased diameter (and hence an increasedupsetting volume). The upsetting die is formed by a substantially flatupper surface 706 of the rod, an upper surface 799 of the sleeve 798,the pip 708 and a collar 730 formed by the housing 700. The height ofthe first surface 795 of the cam 740 is chosen such that the uppersurface 799 of the sleeve 798 is aligned with (or substantially alignedwith) the substantially flat upper surface 706 of the rod 704 when thefastening apparatus is in the configuration shown in FIG. 16.

The slope of the step 743 and the slope 797 provided at the lowermostend of the sleeve 798 may be the same or may be substantially the same.The slopes may provide upward movement of the sleeve 798 when moving thestepped cam 740 from the second configuration (shown in FIG. 16) to thefirst configuration (shown in FIG. 15).

Although the arms 794 of the cam 740 each have two surfaces 795, 796upon which the sleeve 798 may rest, the arms may be provided with adifferent number of surfaces. For example, each arm may be provided withthree, four, five, six or more surfaces.

Although the surfaces 795, 796 are shown as being substantially flat,the surfaces may have some other form. The lowermost end of the sleeve600 may have a corresponding form (e.g. selected to provide asubstantial contact area between the housing and the surfaces).

Although a helical spring 718 is shown, any suitable biasing means maybe used. It is not essential that a biasing means is provided.

A further alternative embodiment of the invention is shown incross-section in FIG. 17. FIG. 17 shows part of a fastener upsetting dieassembly 864 which may be held on a lower jaw of a C-frame (not shown).A rod 804 is held within a bore 801 within a housing 800. Asubstantially flat upper surface 806 of the rod and a collar 830 form anupsetting die. In this embodiment the rod 804 is not provided with a pipat an uppermost surface. However, a pip may be provided. The housing 800is formed in two parts, an upper part 825 and a lower part 827.

An outwardly tapering portion 805 is located at the bottom of an upperportion 807 of the rod 804, the rod 804 having an increased diameterbeneath the outwardly tapering portion. A bore 809 which begins at abottom end of the rod 804 extends into the rod. The bore 809 is threadedand receives a correspondingly threaded bolt 811.

The bore 801 in the housing 800 includes a tapering portion 813, thetapering portion generally corresponding with the tapering portion 805of the rod 804. The bore tapering portion 813 acts to prevent the rod804 from moving upwards within the bore 801 beyond a position at whichthe rod tapering portion 805 comes into contact with the bore taperingportion.

The bore 813 is not threaded, and is configured to allow the rod 804 tofreely move axially within the bore (until the shoulder 805 comes intocontact with the step 813). The rod 804 includes a protrusion 815 whichis received in a correspondingly shaped recess of the bore 801. Theprotrusion 815 is provided on only one side of the rod 804 and therecess is similarly only provided on one side of the bore 801. As aresult, the protrusion 815 prevents the rod 804 from rotating within thebore 801. In general, at least part of the rod and the bore may have anynon-circular cross-sectional shape, thereby preventing the rod fromrotating within the bore.

A lower end of the bolt 811 extends through the bottom of the housing800. A rotating actuator (not shown) may be connected to the lower endof the bolt and used to rotate the bolt. The rotating actuator may becontrolled by a control apparatus (not shown).

The bolt 811 is provided with an intermediate portion 821 with anincreased diameter. The housing 800 may include a corresponding portionwith a corresponding diameter (although this is not shown). Theintermediate portion 821 of the bolt 811 and the corresponding portionof the housing 800 will act to retain the bolt within the housing and tosubstantially prevent axial movement of the bolt within the housing.Although axial movement of the bolt within the housing is substantiallyprevented, the bolt is free to rotate within the housing when it isdriven to rotate by the rotating actuator 819.

In use, the volume of the upsetting die formed by the flat upper surface806 of the rod 804 and the collar 830 is selected by rotating therotating actuator and thereby rotating the bolt 811. Due to the threadedconnection between the bolt 811 and the bore 809 of the rod 804, andbecause the protrusion 815 prevents the rod from rotating, rotation ofthe bolt will force the rod to move axially within the housing 800.Thus, rotation of the bolt 811 in a first direction (e.g. clockwise)will cause the rod 804 to move upwards, thereby reducing the volume ofthe upsetting die. Rotation of the bolt 811 in the opposite directionwill cause the rod 804 to move downwards in the housing, therebyincreasing the volume of the upsetting die. This allows the volume ofthe upsetting die to be modified as desired, for example to accommodatedifferent fastening conditions (e.g. rivets having differentdimensions).

A further alternative embodiment of the invention is shown incross-section in FIG. 18. FIG. 18 shows part of a fastener upsetting dieassembly 964 which may be held on a lower jaw 65 of a C-frame. A rod 904is held within a bore 901 in a housing 900. A substantially flat uppersurface 906 of the rod and a collar 930 form an upsetting die. In thisembodiment the rod 904 is not provided with a pip at an uppermostsurface. However, a pip may be provided.

The housing 900 is secured to a support 950 which is in turn secured tothe lower jaw 65 of the C-frame. The rod 904 is free to move axiallywithin the housing 900. A lower portion of the rod 94 projects out of abottom end of the bore 901. A flange 951 is provided at a lowermost endof the rod 904. A spring 918 extends between the flange 951 and alowermost end of the housing 900, the spring being configured toresiliently bias the flange 951 (and hence the rod) away from thelowermost end of the housing.

A cam follower 952 is provided at a lowermost end of the rod 904. Thecam follower comprises a ball 953 which is received in a recess in aholder 954. The ball 953 has a sloped surface 955 which is configured tocooperate with a sloped cam surface 956 of a cam 957. The cam 957 isconfigured to rotate about an axis of rotation. The cam 957 may beconsidered to be an adjustable end stop. Although the cam followercomprises a ball 953 in a recess in this embodiment, any suitable camfollower may be used.

The cam 957 is driven to rotate by an electric motor 958 (or othersuitable actuator) which his connected to the lower jaw 65 of theC-frame. A cap 959 is attached to the electric motor 958 such that thecap is rotated by the electric motor. The cap 959 is received in anopening 960 in the cam 957, a pin 961 being used to secure the cap tothe cam. The cam 957 is thereby securely attached to the cap 959 suchthat the cam is forced to rotate with the cap. The cam 957 thus rotateswhen the electric motor 958 rotates.

The electric motor 958 includes an encoder which monitors theorientation of the electric motor, and hence monitors the orientation ofthe cam 957. The encoder is connected to control apparatus (not shown)of the fastener apparatus, and provides feedback regarding theorientation of the electric motor 958 (thereby providing feedbackregarding the orientation of the cam 957). This allows the controlapparatus to accurately control the orientation of the cam 957.

In use, the volume of the upsetting die formed by the flat upper surface906 of the rod 904 and the collar 930 is selected by rotating the cam957 using the electric motor 958. Because the cam surface 956 of the cam957 is sloped, rotation of the cam in a first direction will cause theball 953 and rod 904 to move downwards under the resilient bias of thespring 918, and rotation of the cam in an opposite direction will causethe ball and rod to move upwards against the resilient bias of thespring. Thus, the position of the rod 904 in the housing 900 may becontrolled using the electric motor. This allows the upsetting die to bemodified as desired, for example to accommodate different fasteningconditions (e.g. rivets having different dimensions). The volume of theupsetting die is thus controlled by the control apparatus.

A further alternative embodiment of the invention is shown in FIG. 19,the embodiment shown in cross-section in FIG. 19a and in perspectiveview in FIG. 19b . Many features of the embodiment shown in FIG. 19correspond with the embodiment shown in FIG. 18, and these features aretherefore not described again in connection with FIG. 19. Becauselimited space is available, not all of the features are labelled in FIG.19. Unlike the embodiment shown in FIG. 18, an actuator 970 and encoder971 are provided as separate entities. The encoder 971 is locatedbeneath the cam 957 and provides feedback regarding the orientation ofthe cam via an axial connection to the cam. The actuator comprises agrub screw 972 which engages with a cog 973 connected to the cam 957,such that the cog (and hence the cam) rotates when the grub screwrotates. The grub screw 972 is driven to rotate by a motor (not shown),a flexible drive 974 extending from the motor to the grub screw. Theflexible drive 974 may for example include a universal joint 975.

Operation of the embodiment shown in FIG. 19 is the same as operation ofthe embodiment shown in FIG. 18, except that actuation of the cam 957and monitoring of the orientation of the cam are provided separately.

As described above, in the embodiments of the invention illustrated inFIGS. 2 to 6, the resilient bias provided by the helical spring 118, 218pushes the rod 104, 204 away from the adjustable end stop 124, 240. Thismeans that changing the configuration of the adjustable end stop 124,240 does not immediately change the volume of the upsetting die.However, changing the configuration of the adjustable end stop 124, 240selects the upsetting volume of the upsetting die. This is because whenupsetting of a rivet takes place, the helical spring 118, 218 will becompressed such that the upsetting volume of the upsetting die isdetermined by the configuration of the adjustable end stop 124, 240. Inembodiments of the invention in which the rod is not biased upwards,when the configuration of the adjustable end stop (e.g. cam 351, 470,580) is changed, this selects the volume of the upsetting die byimmediately changing the volume of the upsetting die.

The volume of the upsetting die may remain fixed during upsetting of arivet. Alternatively, the upsetting die may be configured to allow itsdiameter (and hence volume) to change passively during upsetting of arivet. In this context the term ‘passively’ may be interpreted asmeaning varying under the influence of force applied by the punch of thefastening apparatus during upsetting of a rivet (i.e. without activecontrol by a control apparatus). For example, the collar of theupsetting die may be formed from a plurality of pieces which areresiliently biased against the rod but which may be displaced outwardsduring upsetting of a rivet. An example of this arrangement is describedin U.S. Pat. No. 7,287,411 which is herein incorporated by reference. Ifthe upsetting die is configured to allow its diameter to changepassively during upsetting of a rivet, the selection of the upsettingvolume may be considered to be the selection of the volume of theupsetting die during upsetting without taking into account passivechanges of the diameter of the die during upsetting.

In embodiments of the invention, selection of the upsetting volume ofthe upsetting die may be controlled by a control apparatus. The controlapparatus may form part of the control system 71 of the fastener system(see FIG. 1) or may be a separate apparatus 73. The control apparatusmay be remote from the upsetting die, and may for example be connectedto an actuator which is configured to adjust the volume of the upsettingdie. Alternatively, the control apparatus may be located adjacent to theupsetting die, for example being located on the C-clamp 63. The controlapparatus may be arranged to receive and store different upsetting dievolumes which are to be used when fastening at different fasteninglocations. During fastening, the control apparatus may refer to thisstored information in order to determine what upsetting die volume isrequired when fastening at a given fastening location, and may thenadjust the upsetting die volume accordingly. The control apparatus mayfor example be an electronic apparatus, for example a microprocessor,and may for example comprise a programmable logic controller. Thecontrol apparatus may for example be part of a more complex controlapparatus, for example a control apparatus which controls movement of arobot upon which the fastening apparatus is provided, and/or controlsdelivery of rivets to the fastening apparatus, and/or controls aproduction line.

The upsetting volume of the upsetting die may be selected according tothe dimensions of a rivet which is to be used in a fastening process.Thus, for example, the control apparatus may store information relatingto the upsetting volumes that are appropriate for rivets with differentdimensions. An operator of the fastening apparatus may input into thecontrol apparatus information which identifies the rivets to be used atdifferent fastening locations. The control apparatus may then refer tothe stored upsetting volume information and use this information toselect an upsetting volume appropriate to the rivet to be used, prior tofastening at each location. The control apparatus may also storeinformation relating to the thickness and/or hardness of the material(s)to be fastened, and may take this information into account whenselecting an upsetting volume to be used at a given fastening location.

In an embodiment, fastening at some locations may be via the use of aclinch joint. Where this is the case, information relating to theupsetting volume of the upsetting die to be used when forming a clinchjoint may be stored by the control apparatus. An operator of thefastening apparatus may input into the control apparatus informationwhich identifies the fastening locations at which a clinch joint is tobe used. The control apparatus may then refer to the stored clinch jointupsetting volume information and use this information to select anappropriate upsetting volume prior to forming a clinch joint.

Additionally or alternatively, the control apparatus may take intoaccount feedback received during a previous fastening process whenadjusting the upsetting volume of the upsetting die. The feedback mayfor example be provided from the punch or from the upsetting die. Forexample, the feedback may comprise the measured movement of the punch(e.g. the stroke of the punch). The movement of the punch may forexample be measured using a measurement sensor such as a transducer(e.g. a linear variable displacement transducer) or one or moreproximity sensors (e.g. inductive proximity sensors). Additionally oralternatively the feedback may comprise the force experienced by thepunch and/or the force experienced by the upsetting die. The force mayfor example be measured using a force sensor such as a load cell orstrain gauge.

The selection of the upsetting volume by the control apparatus may bebased upon the dimensions of a rivet which is to be used and thematerial combination of the workpiece to be fastened. The selection ofthe upsetting volume by the control apparatus may also take into accountfeedback received during one or more previous fastening processes. Thecontrol apparatus may for example determine from the feedback that aprevious fastening process provided sub-optimal fastening, and mayadjust the volume of the upsetting die to provide improved fastening. Inone example, the thickness of the workpiece may be greater thanexpected, and feedback received by the control apparatus may indicatethat sub-optimal fastening has occurred. The control apparatus maydetermine that an increased upsetting volume of the upsetting die willprovide improved fastening, and may then accordingly select an increasedvolume of the upsetting die. For a given type of rivet, the controlapparatus may take into account feedback received when previouslyfastening with that type of rivet, and may exclude feedback receivedwhen fastening with a different type of rivet (e.g. a rivet havingdifferent dimensions). The control apparatus may for example determine adesired upsetting volume by comparing feedback received during insertionof a rivet with feedback recorded during a ‘learning phase’. Thefeedback recorded during the learning phase may for example comprisefeedback received during optimal fastening (or during fastening whichsatisfies one or more quality criteria).

In an embodiment, the fastening apparatus may be used to providefastening with only one type of rivet (or clinching joint) and for onematerial combination. Where this is the case, the selection of theupsetting volume by the control apparatus may be based solely onfeedback received during one or more previous fastening processes. Thecontrol apparatus may for example determine from the feedback that aprevious fastening process provided sub-optimal fastening, and mayadjust the volume of the upsetting die to provide improved fastening. Inone example, the thickness of the workpiece may be less than expected,and feedback received by the control apparatus may indicate thatsub-optimal fastening has occurred. The control apparatus may determinethat a reduced upsetting volume of the upsetting die will provideimproved fastening, and may then accordingly select an increased volumeof the upsetting die.

The above may be considered to be examples of automated selection of theupsetting volume of the upsetting die performed by a control apparatus.The automated selection of the upsetting volume of the upsetting die maybe based upon previously stored information (examples of which are givenabove) and/or based on feedback. 20.

The control apparatus may be capable of selecting an upsetting volume ofthe upsetting die individually for each fastener which is inserted intoa workpiece. This may comprise for example taking into account for eachfastener at least one of: properties of the fastener, properties of theworkpiece, or feedback generating during a previous fastening operation,and then determining whether the upsetting volume of the upsetting dieshould be changed (and changing the upsetting volume if necessary).Although the control apparatus may be capable of selecting an upsettingvolume of the upsetting die individually for each fastener, it is notessential that the control apparatus is configured to do so in allsituations (although the control apparatus may be so configured). Forexample, in some situations the control apparatus may be configured tomaintain a particular upsetting volume for a series of fasteningoperations (e.g. fastening operations which are all performed using thesame type of rivet and using a workpiece having properties which aresubstantially constant for the series of fastening operations).

The upsetting dies provided by embodiments of the invention may includea pip or may not include a pip (either form of upsetting die may beused). The pip may have a shape which differs from the shapes shown inFIGS. 2-6. If a pip is provided then the depth of the die may bemeasured from the upper surface 106, 206, 606, 706, 806, 906 of the rod104, 204, 604, 704, 804, 904 rather than from the top of the pip 108,208, 608, 708. The depth of the die may be measured as the distance fromthe lowermost point in the upsetting die to the top of the collar 130,230, 330, 430, 630, 730, 830, 930 (or top of the sleeve 798 if thesleeve forms sides of the upsetting die). In some instances the pip mayproject above the top of the upsetting die.

Embodiments of the invention may be configured to change the depth ofthe upsetting die for example from a depth of 0 mm to a depth of 1.5 mm,a depth of 3 mm, a depth of 4 mm or more (optionally includingintermediate depths). A selected depth of the upsetting die will dependin part upon the size of the rivets which are to be upset using theupsetting die. The selected depth of the die may scale as the lengthand/or diameter of a rivet increases. Thus, if different future standardrivet sizes are adopted a deeper upsetting die may be selected.

Embodiments of the invention may be configured to change the depth ofthe upsetting die for example between 1.5 mm and 3 mm (optionallyincluding intermediate depths). This may be desirable for example whenusing rivets having a shank diameter of 5.3 mm (this is one of thestandard sizes in which rivets are provided).

Embodiments of the invention may be configured to change the depth ofthe upsetting die for example between 0 mm and 1.5 mm (optionallyincluding intermediate depths). This may be desirable for example whenusing rivets having a shank diameter of 3.3 mm (this is another of thestandard sizes in which rivets are provided).

Embodiments of the invention may be configured to change the depth ofthe upsetting die by increments of less than 0.1 mm Embodiments of theinvention may be configured to change the depth of the upsetting die byincrements of 0.1 mm or more, by increments of 0.2 mm or more, or byincrements of 0.3 mm or more. Embodiments of the invention may beconfigured to change the depth of the upsetting die by increments ofaround 0.25 mm. Embodiments of the invention may be configured toprovide changes of the depth of the upsetting die in a continuousmanner.

Embodiments of the invention may for example allow workpieces havingthicknesses between 1 mm and 15 mm to be riveted using self piercingrivets. Embodiments of the invention may be capable of fasteningworkpieces using rivets having lengths between 3 mm and 18 mm.

The helical spring 118, 218 (or other biasing means) may assist indisengagement of a fastened workpiece and the upsetting die. This isbecause it pushes the fastened workpiece upwards (in embodiments inwhich the workpiece may move upwards) or pushes the upsetting diedownwards (in embodiments in which the upsetting die may movedownwards). Additionally or alternatively, the adjustable end stop 124,240, 351, 470, 580, 957 may disengage or assist in disengagement of thefastened workpiece and the upsetting die. This may be achieved byactuating the adjustable end stop to push the rod 104, 204, 304, 404,904 upwards and thereby push the fastened workpiece and the upsettingdie apart. The adjustable end stop may for example be actuated such thatthe upsetting die has a zero depth or such that the rod protrudes beyondthe top of the housing. The helical spring 118, 218 and/or adjustableend stop 124, 240, 351, 470, 580 may also remove or assist in theremoval of waste material from the upsetting die (the material havingbeen released or sheared from the workpiece during fastener insertion).The waste material may for example be adhesive which has been pressedout of the workpiece during fastening. The workpiece and the wastematerial may both be considered to be examples of workpiece material.

In the embodiment shown in FIGS. 13-14 the helical spring 618 (or otherbiasing means) may act together with the cam 640 to assist in separationof workpiece material and the upsetting die. The cam 640 may for examplebe moved from a configuration which provides an upsetting die having avolume used for insertion of a fastener to a configuration whichprovides a smaller upsetting die volume. The selection of the smallerupsetting die volume, together with the bias provided by the helicalspring 618 may push workpiece material out of the upsetting die.

In the embodiment shown in FIGS. 15-16 the helical spring 718 (or otherbiasing means) may act together with the cam 740 to assist in separationof workpiece material and the upsetting die. The cam 740 may for examplebe moved from a configuration which provides an upsetting die having avolume used for insertion of a fastener to a configuration whichprovides a larger upsetting die volume. This will allow the sleeve 798to move downwards under the bias provided by the helical spring 718,thereby separating the sleeve 798 and the workpiece material andallowing the workpiece material to be removed from the upsetting die.

In an alternative approach, the cam 740 may for example be moved from aconfiguration which provides an upsetting die having a volume used forinsertion of a fastener to a configuration which provides a smallerupsetting die volume. This will push the sleeve 798 upwards such thatthe sleeve pushes the workpiece material upwards, and may push theworkpiece material out of the upsetting die.

In an embodiment, the adjustable end stop 124, 240, 351, 470, 580 or cam640, 740, 957 may be moved from a configuration used for insertion of afastener (or formation of a clinch joint) to a configuration used toseparate workpiece material and the upsetting die after each fasteningprocess.

Changing the configuration of the adjustable end stop 124, 240, 351,470, 580 or cam 640, 740, 957 to separate workpiece material from theupsetting die may for example take place after the punch has beenwithdrawn from the upsetting die or during withdrawal of the punch fromthe upsetting die. Changing the configuration of the adjustable end stopor cam may be combined with movement of the upsetting die away from theworkpiece (e.g. through movement of the C-frame) or with movement of theworkpiece away from the upsetting die.

Although the actuators shown in the embodiments illustrated in FIGS.7-12 are located adjacent to the cams which they are actuating, theactuators may be located away from the cams. Similarly, actuators usedby the embodiments illustrated in FIGS. 2-6 may be located adjacent tothe adjustable end stops or away from the adjustable end stops. Locatingan actuator away from an adjustable end stop may be advantageous. Forexample, the actuator may be located away from parts of the C-clamp 65which are close to a workpiece during fastening of the workpiece,thereby avoiding the possibility that the actuator acts as anobstruction.

Some of the above described embodiments of the invention include a flator substantially flat upper surface at an upper end of the rod. This isnot essential however, and the upper end of the rod may have anysuitable shape.

The above description refers to changing the volume of the upsetting diewhen switching between fastening using rivets having differentdimensions. The volume of the upsetting die may be changed whenswitching between fastening using rivets having different hardnesses (adifferent hardness may require a different upsetting volume even if therivet dimensions are unchanged).

There may be circumstances in which the volume of the upsetting die ischanged when fastening using rivets having the same dimensions and thesame hardness. For example, embodiments of the invention may be used toinsert rivets having the same dimensions and hardness into twoworkpieces having different material combinations, the volume of theupsetting die being changed to accommodate the different materialcombinations. The term “material combination” may refer to thethicknesses of materials which comprise the workpieces and/or may referto the types of material which comprise the workpieces. For example, aworkpiece which includes a layer of adhesive may require a differentupsetting die volume than an equivalent workpiece which does not includea layer of adhesive.

Embodiments of the invention may be used to insert rivets havingdifferent dimensions and/or hardnesses into workpieces comprisingdifferent material combinations.

The fastening apparatus may include a feeder which is capable of feedingrivets having two different geometries (or more) to the nose assembly 68(see FIG. 1) of the fastening apparatus.

The actuators which are used to change the volume of the upsetting diemay for example be electrical, mechanical, hydraulic or pneumatic (e.g.a pneumatic cylinder, piezo-electric actuator, stepper-motor or thelike). They may be controlled by the control apparatus. The actuatorsmay have open or closed loop feedback control, which may allow accuratesetting of the die volume and transition between different desiredvolumes in whatever progression is desired. Feedback (e.g. positionalinformation) from the actuators or from the upsetting die may pass tothe control apparatus, which may take the feedback into account whencontrolling the actuators. The feedback may for example be provided bysensors and/or other detectors.

An implementation of the invention may be in an automated productionline for vehicle bodies where a plurality of robot manipulated systemsare used to insert fasteners. During a typical cycle, a robot may inserta quantity of first fasteners and a quantity of second or thirdfasteners, with the die volume being adjusted between fastenersaccording to which fastener is supplied and/or changes in the workpiecebetween fastening locations. The quantity and sequence of changes to theupsetting volume of the upsetting die, and the upsetting volumeresulting from each change will vary from application to application(for example depending on the change in workpiece and/or fastenerbetween fastening locations). For instance, a robot may insert 15fasteners in a cycle, with 10 fasteners having the first upsettingvolume and then 5 fasteners having the second upsetting volume.Alternatively, the upsetting volume may be adjusted before eachfastener.

In an embodiment, fastening with rivets may be alternated with fasteningwith clinch joints. A clinch joint does not use a fastener but insteaduses a punch to push a workpiece into an upsetting die, fastening beingprovided by deformation of the workpiece. An embodiment of the inventionmay provide fastening with rivets using an upsetting die having anupsetting volume, and may then provide fastening with a clinch jointusing an upsetting die having a different upsetting volume (theupsetting volume of the upsetting die being selected as describedabove).

Computer programs may be provided to instruct the fastening apparatus tocarry out the methods described herein. Such computer programs may becarried on appropriate computer readable media, which term includesappropriate tangible storage devices (e.g. discs).

Although embodiments of the invention have been described in the contextof rivet insertion, the invention may be used with fasteners other thanrivets. In this context the term “fastener” may include rivets(including self-piercing rivets), screws, slugs, weld studs, mechanicalstuds and other types of fastening devices.

Various terms such as vertical, horizontal, lower and higher may be usedin the description of embodiments of the invention. These terms are usedmerely to facilitate description of the embodiments and are not intendedto imply that the faster apparatus or any components of the fasteningapparatus must have a particular orientation.

The term “workpiece” may include any combination of materials andmaterial types, including adhesive, that are to be fastened whether partof the same structure or separate structures.

Features of embodiments of the invention may be used in combination withfeatures of other embodiments of the invention.

The invention claimed is:
 1. A fastening method comprising: (a) using acontrol apparatus to select a first upsetting volume of an upsettingdie, then (b) using a punch to push a first fastener into a workpieceand using the upsetting die to upset the first fastener, then (c) usingthe control apparatus to select a second upsetting volume of theupsetting die, then (d) using the punch to push a second fastener into aworkpiece and using the upsetting die to upset the second fastener, orusing the punch and the upsetting die to form a clinch joint, whereinthe upsetting volume of the upsetting die is fixed during upsetting ofat least one of the first fastener and the second fastener.
 2. Themethod of claim 1, wherein the selection of the upsetting volume of theupsetting die by the control apparatus is automated.
 3. The method ofclaim 2, wherein the selection of the upsetting volume of the upsettingdie is based on previously stored information and/or feedback.
 4. Themethod of claim 3, wherein the feedback includes one or more of movementof the punch, force experienced by the punch and force experienced bythe upsetting die.
 5. The method of claim 3, wherein the controlapparatus determines and selects an upsetting volume of the upsettingdie which will provide improved fastening based upon the feedback. 6.The method of claim 1, wherein the method further comprises againselecting the first upsetting volume of the upsetting die, and using thepunch to push a subsequent fastener into a workpiece and using theupsetting die to upset the subsequent fastener.
 7. The method of claim1, wherein selecting the upsetting volume of the upsetting die comprisesselecting the depth of the upsetting die.
 8. The method of claim 1,wherein the upsetting die is at least partially formed by a surface of arod located in a bore, the rod being moved within the bore to change theupsetting volume of the upsetting die.
 9. The method of claim 8, whereinthe position of the rod within the bore is determined by an adjustableend stop.
 10. The method of claim 9, wherein the adjustable end stopcomprises a cam which is moveable between a plurality of configurationswhich determine the position of the rod within the bore.
 11. The methodof claim 10, wherein the cam is a plate which is configured to rotateabout an axis of rotation.
 12. The method of claim 1, wherein theupsetting die is at least partially formed by a surface of a rod locatedin a bore in a housing, the housing being moved relative to the rod tochange the upsetting depth of the upsetting die.
 13. The method of claim1, wherein the upsetting die is at least partially formed by a surfaceof a rod located in a bore in a housing and is at least partially formedby a sleeve located between the rod and the housing, the sleeve beingmoved relative to the rod and the housing to change the upsettingdiameter of the upsetting die.
 14. The method of claim 1, wherein thefirst fastener and the second fastener have different dimensions and/orhardnesses.
 15. The method of claim 1, wherein the first fastener andthe second fastener have the same dimensions, and the workpiece intowhich the second fastener is pushed comprises a combination of materialswhich is different than the combination of materials which comprises theworkpiece into which the first fastener is pushed.
 16. The method ofclaim 1, wherein the selection of the second upsetting volume of theupsetting die is performed whilst the punch and upsetting die are movingbetween a first fastening location and a second fastening location, orwhilst the workpiece is being moved between a first fastening locationand a second fastening location.
 17. The method of claim 1, wherein theupsetting volume of the upsetting die is selected using an actuator. 18.The method of claim 1, wherein the method further comprises selecting avolume which is different from the first upsetting volume or the secondupsetting volume and thereby separating or assisting in separation ofworkpiece material and the upsetting die.
 19. A fastening apparatuscomprising: a punch and an upsetting die, wherein the upsetting volumeof the upsetting die is adjustable; an actuator and control apparatuswhich are configured to adjust the upsetting volume of the upsettingdie, the control apparatus being capable of selecting an upsettingvolume of the upsetting die individually for each fastener which isinserted into a workpiece, wherein the upsetting volume of the upsettingdie is fixed during upsetting of the fasteners.
 20. The apparatus ofclaim 19, wherein the control apparatus is configured to select theupsetting volume of the upsetting die in an automated manner.
 21. Theapparatus of claim 19, wherein the control apparatus is configured toselect the upsetting volume of the upsetting die based on previouslystored information and/or feedback.
 22. The apparatus of claim 19,wherein the actuator and control apparatus are configured to fix theupsetting volume of the upsetting die during upsetting of the fasteners.23. The control apparatus of claim 19, wherein the control apparatus iscapable of selecting an upsetting volume which is suitable for forming aclinch joint.
 24. The apparatus of claim 19, wherein the upsetting dieis at least partially formed by a surface of a rod located in a bore,the rod being movable within the bore to change the upsetting volume ofthe upsetting die.
 25. The apparatus of claim 24, wherein the apparatusfurther comprises an adjustable end stop which is configured todetermine the position of the rod within the bore during upsetting of afastener.
 26. The apparatus of claim 25, wherein the adjustable end stopcomprises a cam which is moveable between a plurality of configurationswhich determine the position of the rod within the bore.
 27. Theapparatus of claim 26, wherein the cam is a plate which is configured torotate about an axis of rotation.
 28. The apparatus of claim 19, whereinthe upsetting die is at least partially formed by a surface of a rodlocated in a bore in a housing, the housing being moveable relative tothe rod to change the upsetting depth of the upsetting die.
 29. Theapparatus of claim 19, wherein the upsetting die is at least partiallyformed by a surface of a rod located in a bore in a housing and is atleast partially formed by a sleeve located between the rod and thehousing, the sleeve being moveable relative to the rod and the housingto change the upsetting diameter of the upsetting die.
 30. The apparatusof claim 19, wherein the apparatus further comprises one or more sensorswhich are configured to provide feedback to the control apparatus whichis measured during fastening.
 31. The apparatus of claim 30, wherein thecontrol apparatus is configured to determine and select an upsettingvolume of the upsetting die which will provide improved fastening basedupon the feedback.
 32. The apparatus of claim 30, wherein the one ormore sensors are configured to measure one or more of the movement ofthe punch, force experienced by the punch and force experienced by theupsetting die.
 33. The apparatus of claim 19, wherein the controlapparatus is configured to change the upsetting volume of the upsettingdie whilst the fastening apparatus is moving between a first fasteninglocation and a second fastening location, or whilst the workpiece ismoving between a first fastening location and a second fasteninglocation.
 34. The apparatus of claim 19, wherein the control apparatusis configured to select a volume which is different from the upsettingvolume after a fastener has been upset, thereby separating or assistingin separating workpiece material and the upsetting die.
 35. Thefastening apparatus of claim 19, within a fastening system which furthercomprises a rivet feeding system and a control system.
 36. A method ofmanufacturing vehicles comprising: (a) using a control apparatus toselect a first upsetting volume of an upsetting die, then (b) using apunch to push a first fastener into a workpiece and using the upsettingdie to upset the first fastener, then (c) using the control apparatus toselect a second upsetting volume of the upsetting die, then (d) usingthe punch to push a second fastener into a workpiece and using theupsetting die to upset the second fastener, or using the punch and theupsetting die to form a clinch joint, and (e) inserting the first andsecond fasteners into a workpiece, wherein the upsetting volume of theupsetting die is fixed during upsetting of at least one of the firstfastener and the second fastener.